Funnily enough, I was thinking of John Ogden and hearing him playing an evening of Chopin at Worksop College many years ago. (He was an old boy.) I was interested to see he didn't have a musical score to play to, as I had been taught to do so.

When I started playing in folk clubs, it was difficult to make that bridge from playing in an orchestra where I had the music and tempo as a crutch, regardless of how well I knew the piece and it took time to be "free and easy" even when it was just me and a guitar.

But, and this is the big but for me in this debate...

Although I played to "dots" I knew them inside out, through practice and rehersal. Having the score in front of me, I could concentrate on the expression rather than the mechanics.

In a singaround of just singing, knowing the song is still important. I have yet to see anybody's folder words include breathe points or other cues. Sight reading a song means you are concentrating on the words rather than how to sing them.

No matter how age or natural inability precludes memorising words, you can still learn the song, learn how to make the most of cadence points, crescendos and expression. The words in front of you should be a guide, not something you are experiencing milliseconds before your audience.
After all, you aren't in the bath. You are trying to entertain people and that doesn't take talent, it merely takes courtesy. Courtesy of doing your best. Crafting the words isn't skill but practice.

Assuming those who sound good are just talented isn't a good assumption. I assume they have practiced the song and thought about how to present it. Any natural skill is tempered by practice. the more you prepare, the more "naturally talented" you come over.

You owe to to those spending their time listening to entertain them. If it isn't entertaining, what is it??